Asia's middle-class population may be swelling, but the rich-poor divide is still big. The reasons for this inequality are many, but one key culprit is the lack of inheritance and gift taxes in most of the region's emerging economies. The wealth gap is most glaring in Malaysia. According to the World Bank, the country's richest 10% earn about 20 times more than the poorest 10% on average. In China, Singapore, the Philippines and Thailand, the gulf is greater than a factor of 10. A widening rift between Thailand's poorer villagers and wealthier urbanites contributed to political instability that sparked a military coup in May.